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trouble with receiver sansui g4500 fm got a noise

Good nights, evreyone my sansui g4500 got some noise on fm band the stations are good reception an sound good, but there´s a noise lake a ffffrrrrrr, on the back when speak and plays soft music on radio fm, makes a ffffrrr, i replace a 80% of electrolytics, in the part of radio and amp too, somebody can give me soem tips for repair?, thnkx v.m.